To pay or not to pay? A decision and cost-utility analysis of angiotensin-converting-enzyme inhibitor therapy for diabetic nephropathy.

BACKGROUND: Angiotensin-converting-enzyme (ACE) inhibitor therapy can significantly delay the progression of diabetic nephropathy to end-stage renal failure (ESRF). The main obstacle to successful compliance with this therapy is the cost to the patients. The authors performed a cost-utility analysis from the government's perspective to see whether the province or territory should pay for ACE inhibitors for type I diabetic nephropathy on the assumption that cost is a major barrier to compliance with this important therapy. METHODS: A decision analysis tree was created to demonstrate the progression of type I diabetes with macroproteinuria from the point of prescription of ACE inhibitor therapy through to ESRF management, with a 21-year follow-up. Drug compliance, cost of ESRF treatment, utilities and survival data were taken from Canadian sources and used in the cost-utility analysis. One-way and two-way sensitivity analyses were performed to test the robustness of the findings. RESULTS: Compared with a no-payment strategy, provincial payment of ACE inhibitor therapy was found to be highly cost-effective: it resulted in an increase of 0.147 in the number of quality-adjusted life-years (QALYs) and an annual cost savings of $849 per patient. The sensitivity analyses indicated that the cost-effectiveness depends on compliance, effect of benefit and the cost of drug therapy. Changes in the compliance rate from 67% to 51% could result in a swing in cost-effectiveness from a savings of $899 to an expenditure of more than $1 million per additional QALY. A 50% reduction in the cost of ACE inhibitors would result in a cost savings of $299 per additional QALY with compliance rates as low as 58% in the provincial payment strategy. INTERPRETATION: Provincial coverage of ACE inhibitor therapy for type I diabetes with macroproteinuria improves patient outcomes, with a decrease in cost for ESRF services.